"It's probably somebody who already had a substantial position. This would be easily scanned" by regulators, Najarian said. "When you trade with eight minutes to go for the day and at the numbers these were at, you would be putting a big bullseye on yourself."

Traders marveled, though, both at the closing activity Wednesday and the stampede before the opening Thursday.

That spilled over into Thursday trading, when money poured in hoping to get ahead of the huge rains Facebook looked ready to roll up.

"I've never seen a stock with this big of a float this strong," Rovelli said. "People were trying to short it—they just ripped right through it. Whoever was buying the stock at the opening, I never saw anyone that aggressive. It was nuts."

On the options trading Wednesday, the action was equally intense in the minutes before the Facebook earnings release, which saw the company post earnings per share of 19 cents, ahead of estimates for 14 cents. Revenue of $1.81 million also easily beat the Wall Street view.

Shares jumped after hours and rose as much as 26 percent in Thursday trading.

Multiple 10,000-contract trades took place just before the release, with most of the action on the long side as traders shorted put spreads and bought call spreads, Najarian said.

One trader had the August spread purchased for 75 cents and sold for $2.75, netting a $2.05 million profit. Another had the January spread purchased for 71 cents and sold at $2.65, netting a $1.94 million profit.

Spread trading involves buying an equal amount of options for a company but with different "strike," or target, prices, and hoping to capture the spread between the prices.

The Thursday stock movement helped Facebook regain some dignity after a rough year since its initial public offering, which priced at $38 a share. Even with the big gain, shares remain 13 percent from the IPO level.

"There's an air pocket basically from where it was last night all the way up to $34, maybe even up to $38," Najarian said. "For whatever reason, most of the experts were completely flat-footed."